Dial gauge

ABSTRACT

A dial gauge ( 1 A) has stem bush ( 20 ) having a fitting ( 21 ) fitted to an inner wall of a stem ( 5 ) and having a predetermined clearance between a spindle ( 3 ), a holder ( 22 ) for slidably holding the spindle ( 3 ) while securing a predetermined clearance against the inner wall of the stem ( 5 ), and an elastically deformable connector ( 23 ) for connecting the fitting ( 21 ) and the holder ( 22 ), whereby an influence of deformation of the stem ( 5 ) and the fitting ( 21 ) on the holder ( 22 ) during clamping can be minimized, so that the dial gauge ( 1 A) can be fixed to a supporting stand without deteriorating slidability of the spindle ( 3 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a dial gauge. More specificallyit relates to a dial gauge for detecting a displacement of a spindle tomeasure a dimension of a workpiece.

[0003] 2. Description of Related Art

[0004] A dial gauge 1 shown in FIGS. 7 and 8 is known as a measuringinstrument for measuring a dimension of a workpiece.

[0005] The dial gauge 1 has a spindle 3 having a probe 2 to be incontact with the workpiece at a distal end thereof, a body 4 having adisplay 4B for displaying a measured value by a pointer 4A, and acylindrical stem 5 provided to the body 4 for slidably holding thespindle 3 through a stem bush 10, the dimension of the workpiece ismeasured by detecting a displacement of the spindle 3 relative to thebody 4. Among the above components, the stem bush 10 is formed in acylindrical shape having outer circumference being fixed to an innerwall of the stem 5 and inner circumference slidably holding the spindle3. A predetermined clearance is formed between the inner circumferenceof the stem bush 10 and the outer circumference of the spindle 3. Thestem bush 10 is located on the probe 2 side of the stem 5.

[0006] The dial gauge 1 sometimes is used to measure the workpiece whilebeing mounted to a supporting stand 6 as shown in FIG. 7.

[0007] The supporting stand 6 has a base 6B having a measuring table 6Aon an upper surface thereof, a column 6C standing of the base 6B, and abracket 6D vertically movable along the column 6C with the dial gauge 1held thereon. The bracket 6D has a clamp hole 61 for the stem 5 of thedial gauge 1 to be inserted, a slitting groove 62 extending from theclamp hole 61 to an end (an end remote from the column 6C) of thebracket 6D, and a clamp screw 63 for elastically deforming the end ofthe bracket 6D to narrow the width of the slitting groove 62.

[0008] In use, after the stem 5 of the dial gauge 1 is inserted to theholding hole 61 of the bracket 6D, the dial gauge 1 is fixed to thebracket 6D by clamping the clamp screw 63. At this time, a clampposition 5A (outline arrow in FIG. 8) of the stem 5 by the clamp screw63 is remote from the stem bush 10 by a predetermined distance along anaxial direction of the spindle 3. In this state, after the spindle 3 ofthe dial gauge 1 is once lifted, the workpiece is set on the measuringtable 6A. Subsequently, the spindle 3 is lowered so that the probe 2abuts the workpiece. The height of the workpiece is measured by readingthe dial gauge at the time.

[0009] However, since the above-described dial gauge 1 is mounted to thebracket 6D of the supporting stand 6 by clamping the stem 5 with theclamp screw 63, the stem 5 can be slightly deformed on account of theclamp force of the clamp screw 63 for clamping the stem 5. When the stem5 is deformed, the stem bush 10 fitted to the inner wall of the stem 5also deforms. The deformation of the stem bush 10 can bring the innercircumference of the stem bush 10 into contact with the outercircumference of the spindle 3, so that the inner circumference of thestem bush 10 holds the outer circumference of the spindle 3, thusdeteriorating slidability of the spindle 3.

[0010] In order to overcome the above disadvantage, the clearancebetween the spindle 3 and the stem bush 10 may be set wide. However,when the clearance is enlarged, shaky movement of the spindle 3 relativeto the stem bush 10 can be magnified, so that the measurement accuracycan be deteriorated.

SUMMARY OF THE INVENTION

[0011] According to an aspect of the present invention, a dial gaugeincludes: a spindle having a probe to be in contact with a workpiece ata distal end thereof; a body; and a stem provided to the body forslidably holding the spindle through a stem bush, the stem bush having:a fitting fitted to an inner wall of the stem while securing apredetermined clearance against the spindle; a holder for slidablyholding the spindle, and having a predetermined clearance against theinner wall of the stem; and an elastically deformable connector forconnecting the fitting and the holder, the clearance between the fittingand the spindle being larger than the clearance between the holder andthe spindle.

[0012] When the dial gauge is mounted to the supporting stand byclamping the stem, the stem can be deformed by the clamping force. Sincethe clearance between the fitting and the spindle is set large in thestem bush, the inner circumference of the fitting is not in contact withthe outer circumference of the spindle even when the fitting secured tothe inner wall of the stem is deformed in accordance with deformation ofthe stem. On the other hand, since the clearance between the stem andthe holder is large, the inner wall of the deformed stem is not incontact with the outer circumference of the holder. In other words, theinner circumference of the holder is not pressed against the outercircumference of the spindle by the stem.

[0013] Further, since the fitting and the holder of the stem bush isconnected by the elastically deformable connector, even when the fittingis deformed in accordance with the deformation of the stem, most of thedeformation is absorbed by the elastic deformation of the connector, sothat the deformation of the fitting is not directly transferred to theholder, thus minimizing the deformation of the holder. In other words,deterioration of slidability of the spindle relative to the stem bushcan be minimized. Accordingly, even when the stem is deformed in fixingthe dial gauge to the supporting stand, the deterioration of slidabilityof the spindle relative to the stem bush can be prevented.

[0014] Further, since the deformation of the holder in accordance withdeformation of the stem is smaller than the conventional arrangement,the clearance between the holder and the spindle can be made smallerthan the conventional arrangement without influencing on the slidabilityof the spindle. Accordingly, the shaky movement of the spindle and theholder can be made smaller than the conventional arrangement, thusimproving the measurement accuracy.

[0015] In an arrangement of the present invention, the fitting maypreferably be formed in a cylinder, and the holder may preferably beformed in a cylinder having a diameter corresponding to a diameter ofthe spindle.

[0016] Accordingly, since the fitting is cylindrically formed, bondingarea of the fitting against the inner wall of the stem can be enlarged,thus securely fixing the fitting to the inner wall of the stem. Further,since the holder is cylindrical, the slide movement of the spindle inaxial direction can be stabilized.

[0017] In an arrangement of the present invention, the fitting and theholder may preferably be spaced apart along an axial direction of thespindle, and the connector may preferably be a tapered cylinderconnecting the fitting and the holder, one end of the connector having adiameter corresponding to the diameter of the fitting and the other endof the connector having a diameter corresponding to the diameter of theholder.

[0018] Accordingly, since the fitting and the holder are connected bythe cylindrical connector having diameters of both ends corresponding tothe diameter of the fitting and the holder respectively, the fitting canbe strongly connected to the holder.

[0019] In the above arrangement, the holder may preferably located inthe cylinder of the fitting, and the connector may preferably connectmutually adjacent ones of ends of the fitting and the holder, thethickness of the connector being smaller than the respective thicknessof the fitting and the holder.

[0020] Accordingly, since the holder is provided in the cylinder of thefitting, the stem bush of the present invention can be used to a stem ofshort length. Further, since the thickness of the connector is smallerthan respective thickness of the fitting and the holder, the connectoris more easily deformed than the fitting and the holder, thus moreeffectively absorbing the deformation of the fitting by the connector.

[0021] In an arrangement of the present invention, the fitting and theholder may preferably be spaced apart along an axial direction of thespindle, and the connector may preferably connect a part of mutuallyopposing ends of the fitting and the holder, the connector being thinnerthan the respective cylinders of the fitting and the holder.

[0022] Accordingly, since a part of mutually opposing ends of thefitting and the holder is connected by the connector, the size ofconnecting portion of the fitting and the holder can be reduced, thusreducing transmission of the deformation of the fitting toward theholder. Further, since the connector is thinner than the fitting and theholder, the connector is more easily deformed than the fitting and theholder, thus more effectively absorbing the deformation of the fittingby the connector.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a cross section showing a primary portion of a dialgauge according to first embodiment of the present invention;

[0024]FIG. 2 is an enlarged perspective view showing a stem bush of theaforesaid first embodiment;

[0025]FIG. 3 is a cross section showing a primary portion of a dialgauge according to second embodiment of the present invention;

[0026]FIG. 4 is an enlarged perspective view showing a stem bush of theaforesaid second embodiment;

[0027]FIG. 5 is a cross section showing a primary portion of a dialgauge according to third embodiment of the present invention;

[0028]FIG. 6 is an enlarged perspective view showing a stem bush of theaforesaid third embodiment;

[0029]FIG. 7 is an entire perspective view showing a conventional dialgauge and a supporting stand; and

[0030]FIG. 8 is an enlarged cross section showing a primary portion ofthe conventional dial gauge.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0031] Preferred embodiments of the present invention will be describedbelow with reference to attached drawings.

[First Embodiment]

[0032]FIG. 1 shows a dial gauge 1A of the first embodiment of thepresent invention. As in the conventional dial gauge 1, the dial gauge1A has a spindle 3 having a probe (not shown) to be in contact with theworkpiece at a distal end thereof, a body 4 having a display (not shown)for displaying a measured value by a pointer, and a stem 5 provided tothe body 4 for slidably holding the spindle 3 through a stem bush 20,where a dimension of the workpiece is measured by detecting adisplacement of the spindle 3 relative to the body 4.

[0033] As shown in FIG. 2, the stem bush 20 has a fitting 21 fitted toan inner wall of the stem 5 and securing a predetermined clearanceagainst the spindle 3, a holder 22 for slidably holding the spindle 3,the holder 22 securing a predetermined clearance against the inner wallof the stem 5, and an elastically deformable connector 23 for connectingthe fitting 21 and the holder 22. The fitting 2l, the connector 23 andthe holder 22 are sequentially disposed along an axial direction of thespindle 3. The stem bush 20 is located on the probe side of the stem 5.

[0034] The fitting 21 is a cylinder with an outer circumference thereoffitted to the inner wall of the stem 5. The holder 22 is a cylinderhaving an inner diameter corresponding to the outer diameter of thespindle 3, where a predetermined clearance is secured between the innercircumference of the holder 22 and the outer circumference of thespindle 3.

[0035] The connector 23 is a cylinder having trapezoidal side face withone end thereof (an end on the right side of FIG. 2) corresponding tothe diameter of the fitting 21 and the other end (an end on the leftside in FIG. 2) corresponding to the diameter of the holder 22, thusconnecting the fitting 21 and the holder 22.

[0036] The clearance between the fitting 21 and the spindle 3 and theclearance between the holder 22 and the stem 5 are larger than theclearance between the holder 22 and the spindle 3.

[0037] Next, a function of the present invention will be describedbelow.

[0038] The dimension of the workpiece is measured using the dial gauge1A while the dial gauge 1A is mounted to the conventional supportingstand 6 (see FIG. 7). In order to mount the dial gauge 1A to thesupporting stand 6, as described above, after the stem 5 of the dialgauge 1A is inserted to the clamp hole 61 of the bracket 6D, the clampscrew 63 is clamped to fix the dial gauge 1A to the bracket 6D. In thiscondition, the clamp position 5A (outline arrow in FIG. 1) is located atpredetermined distance away from the stem bush 10 along the axialdirection of the spindle 3.

[0039] When the clamp screw 63 is clamped, simultaneously with deformingthe stem 5 by the clamp force, the fitting 21 fitted to the inner wallof the stem 5 is also deformed. Since a predetermined clearance isformed between the fitting 21 and the spindle 3, the fitting 21 does notabut the spindle 3.

[0040] Since the predetermined clearance is secured between the stem 5and the holder 22, the stem 5 does not directly touch the holder 22 evenwhen the stem 5 is deformed, so that the deformation of the holder 22 isnot deformed on account of the contact of the stem 5 against the holder22. Further, since large part of the deformation of the fitting 21 inaccordance with the deformation of the stem 5 is absorbed by the elasticdeformation of the connector 23, the influence on the holder 22 by thedeformation of the fitting 21 is reduced.

[0041] Accordingly, even when the stem 5 is fixed to the bracket 6D ofthe supporting stand 6, the deformation of the holder can be minimized,so that the slidability of the spindle 3 can be maintained atsubstantially the same level as before being fixed to the bracket 6D.

[0042] While the dial gauge 1A is mounted to the supporting stand 6, theworkpiece is set on the measuring table 6A after the spindle 3 of thedial gauge 1A is once raised. Subsequently, the spindle 3 is lowered tobring the probe 2 into contact with the workpiece. The height dimensionof the workpiece is measured by reading the dial gauge at the time.

[0043] According to the above-described embodiment, following effectscan be obtained.

[0044] (1) When the dial gauge 1A is mounted to the supporting stand 6by clamping the stem 5, the stem 5 can be deformed by the clampingforce. Since the clearance between the fitting 21 and the spindle 3 isset large in the stem bush 20, the inner circumference of the fitting 21is not in contact with the outer circumference of the spindle 3 evenwhen the fitting 21 secured to the inner wall of the stem 5 is deformedin accordance with deformation of the stem 5. On the other hand, sincethe clearance between the stem 5 and the holder 22 is large, the innerwall of the deformed stem 5 is not in contact with the outercircumference of the holder 22. In other words, the inner circumferenceof the holder 22 is not pressed against the outer circumference of thespindle 3 by the stem 5.

[0045] Further, since the fitting 21 and the holder 22 of the stem bush2 is connected by the elastically deformable connector 23, even when thefitting 21 is deformed in accordance with the deformation of the stem 5,most of the deformation is absorbed by the elastic deformation of theconnector 23, so that the deformation of the fitting 21 is not directlytransferred to the holder 22, thus minimizing the deformation of theholder 22. In other words, deterioration of slidability of the spindle 3relative to the stem bush 20 can be minimized. Accordingly, even whenthe stem 5 is deformed in fixing the dial gauge 1A to the supportingstand 6, the deterioration of slidability of the spindle 3 relative tothe stem bush 20 can be prevented.

[0046] Further, since the deformation of the holder 22 in accordancewith deformation of the stem 5 is smaller than the conventionalarrangement, the clearance between the holder 22 and the spindle 3 canbe made smaller than the conventional arrangement without influencing onthe slidability of the spindle 3. Accordingly, the shaky movement of thespindle 3 and the holder 22 can be made smaller than the conventionalarrangement, thus improving the measurement accuracy.

[0047] (2) Since the fitting 21 is cylindrically formed in the stem bush20, bonding area of the fitting 21 against the inner wall of the stem 5can be enlarged, thus securely fixing the fitting 21 to the inner wallof the stem 5. Further, since the holder 22 is cylindrical, the slidemovement of the spindle 3 in axial direction can be stabilized.

[0048] (3) Since the fitting 21 and the holder 22 of the stem bush 20 isconnected by the cylindrical connector 23 having both ends diametersrespectively corresponding to the diameter of the fitting 21 and theholder 22, the fitting 21 can be strongly connected to the holder 22.

[Second Embodiment]

[0049]FIG. 3 shows a dial gauge 1B of the second embodiment of thepresent invention. Since the present embodiment differs from theabove-described first embodiment only in the shape of the stem bush andthe other arrangement and functions are the same, the same componentwill be applied with the same reference numeral to omit or simplify thedescription thereof.

[0050] As shown in FIG. 4, the stem bush 30 has a fitting 31 fixed to aninner wall of the stem 5 and having a predetermined clearance betweenthe spindle 3, a holder 32 for slidably holding the spindle 3, theholder 32 securing a predetermined clearance against the inner wall ofthe stem 5, and an elastically deformable connector 33 for connectingthe fitting 31 and the holder 32.

[0051] The fitting 31 is cylindrically formed with an outercircumference thereof fitted to the inner wall of the stem 5. The holder32 is a cylinder having an inner diameter corresponding to the outerdiameter of the spindle 3, where a predetermined clearance is formedbetween the inner circumference of the holder 32 and the outercircumference of the spindle 3. The holder 32 is located inside thecylinder of the fitting 31, so that a predetermined clearance is securedbetween the inner circumference of the fitting 31 and the outercircumference of the holder 32.

[0052] The connector 33 connects mutually adjacent ones of ends of thefitting 31 (an end on the right side of FIG. 4) and the holder 32 (anend on the right side in FIG. 4), where the thickness of the connector33 is smaller than respective thickness of the fitting 31 and the holder32.

[0053] The clearance between the fitting 31 and the holder 32 is largerthan the clearance between the holder 32 and the spindle 3.

[0054] According to the above-described embodiment, following effect aswell as the effects (1) and (2) of the first embodiment can be obtained.(4) Since the holder 32 of the stem bush 30 is provided in the cylinderof the fitting 31, the stem bush 30 of the present invention can beinstalled to a stem of short length. Further, since the thickness of theconnector 33 is smaller than the respective thickness of the fitting 31and the holder 32, the connector 33 can be deformed more easily than thefitting 31 and the holder 32, so that the deformation of the fitting 31can be more effectively absorbed by the connector 33.

[Third Embodiment]

[0055]FIG. 5 shows a dial gauge 1C of the third embodiment of thepresent invention. Since the present embodiment differs from theabove-described first and second embodiments only in the shape of thestem bush and the other arrangement and functions are the same, the samecomponent will be applied with the same reference numeral to omit orsimplify the description thereof.

[0056] As shown in FIG. 6, the stem bush 40 has a fitting 41 fixed to aninner wall of the stem 5 and having a predetermined clearance againstthe spindle 3, a holder 42 for slidably holding the spindle 3, theholder 42 securing a predetermined clearance against the inner wall ofthe stem 5, and an elastically deformable connector 43 for connectingthe fitting 41 and the holder 42. The fitting 41, the connector 43 andthe holder 42 are sequentially arranged along the axial direction of thespindle 3.

[0057] The fitting 41 is cylindrically formed with an outercircumference thereof fixed to the inner wall of the stem 5. The holder42 is a cylinder having an inner diameter corresponding to the outerdiameter of the spindle 3, where a predetermined clearance is formedbetween the inner circumference of the holder 42 and the outercircumference of the spindle 3.

[0058] The connector 43 connects parts of mutually opposing ends of thefitting 41 and the holder 42, and the thickness of the connector 43 isthinner than the thickness of the respective cylinders of the fitting 41and the holder 42. The connector 43 is continuously formed in crescentshape of which both sides extends on an end of the fitting 41 (an end onthe right side of FIG. 6) and an end of the holder 42 (an end on theleft side in FIG. 6), thus connecting the fitting 41 and the holder 42.

[0059] The clearance between the fitting 41 and the holder 42 and theclearance between the holder 42 and the stem 5 are larger than theclearance between the holder 42 and the spindle 3.

[0060] According to the above-described embodiment, following effect aswell as the effects (1) and (2) of the first embodiment can be obtained.(5) Since a part of the mutually opposing ends of the fitting 41 and theholder 42 of the stem bush 40 is connected by the connector 43, the sizeof the connecting portion between the fitting 41 and the holder 42 canbe reduced, so that the deformation of the fitting 41 is less likely tobe transferred to the holder 42. Further, since the thickness of theconnector 43 is thinner than the thickness of the fitting 41 and theholder 42, the connector 43 can be more easily deformed by the fitting41 and the holder 42, so that the deformation of the fitting 41 can bemore effectively absorbed by the connector 43.

[Modifications]

[0061] Incidentally, the scope of the present invention is notrestricted to the above-described embodiment, but includes modificationsand improvements as long as an object of the present invention can beachieved.

[0062] For instance, though a display for displaying measured value by apointer is provided to the body 4 of the dial gauges 1A, 1B and 1C, thedisplay may electrically indicate the measured value, which is alsoincluded in the scope of the present invention.

[0063] Though the dial gauges 1A, 1B and 1C are mounted to thesupporting stand 6 to measure the workpiece, the dial gauge may be fixedusing other supporting stands, or alternatively, the dial gauge may notbe mounted to the supporting stand.

What is claimed is:
 1. A dial gauge, comprising: a spindle having aprobe to be in contact with a workpiece at a distal end thereof; a body;and a stem provided to the body for slidably holding the spindle througha stem bush, wherein the stem bush has: a fitting fitted to an innerwall of the stem while securing a predetermined clearance against thespindle; a holder for slidably holding the spindle, and having apredetermined clearance against the inner wall of the stem; and anelastically deformable connector for connecting the fitting and theholder, the clearance between the fitting and the spindle being largerthan the clearance between the holder and the spindle.
 2. The dial gaugeaccording to claim 1 , wherein the fitting is formed in a cylinder, andwherein the holder is formed in a cylinder having a diametercorresponding to a diameter of the spindle.
 3. The dial gauge accordingto claim 2 , wherein the fitting and the holder are spaced apart alongan axial direction of the spindle, and wherein the connector is atapered cylinder connecting the fitting and the holder, one end of theconnector having a diameter corresponding to the diameter of the fittingand the other end of the connector having a diameter corresponding tothe diameter of the holder.
 4. The dial gauge according to claim 2 ,wherein the holder is located in the cylinder of the fitting, andwherein the connector connects mutually adjacent ones of ends of thefitting and the holder, the thickness of the connector being smallerthan the respective thickness of the fitting and the holder.
 5. The dialgauge according to claim 2 , wherein the fitting and the holder arespaced apart along an axial direction of the spindle, and wherein theconnector connects a part of mutually opposing ends of the fitting andthe holder, the connector being thinner than the respective cylinders ofthe fitting and the holder.